Thirteen patients, aged 1.7 to 16 years, with opsoclonus-myoclonus syndrome were evaluated for neuropsychological, psychosocial and adaptive function at the Children’s National Medical Center, George Washington University, Washington, DC. IQs of six older children ranged from 50 to 72 on the Wechsler scales. One infant had a Mental Index of 71 on the Bayley, and a 46-month-old child tested at the 20-month level. Severe problems related to motor output, involving ambulation, fine motor coordination and speech, while some age-appropriate cognitive skills were retained. Verbal and visual reasoning approached the borderline to normal range. On the Achenbach Child Behavior Checklist, mild to moderately severe behavioral irritability and emotional lability were reported in 8 of 12 non-medicated children. On Vineland Adaptive Behavior Scales, severe adaptive limitations were noted; self-care was significantly delayed in areas related to feeding, dressing and toileting. Motor problems contributed to low scores in daily living and communication scales. One child, aged 8 years examined while treated with ACTH, tested in the normal range. 
COMMENT. In 27 patients with opsoclonus-myoclonus syndrome reported previously from the same center (Pranzatelli et al. 1995, see Ped Neur Briefs March 1995;9:19), the etiology was paraneoplastic in 46% and infectious in the remainder. Hammer, Larsen, and Stack, at Children’s Memorial Hospital, Chicago, have reported on the developmental outcome of 11 children with opsoclonus-myoclonus syndrome, the majority having an associated neuroblastoma. (See Ped Neur Briefs August 1995;9:61). Delayed development with motor incoordination and speech delay occurred in 8 patients and 3 had behavioral problems. Development was normal in 2 of 3 patients without neuroblastoma and in only 1 of 8 whose opsoclonus was associated with neuroblastoma. While the majority of patients in this study had significant developmental delay, others have reported a 50% incidence of intellectual deficit. The poor outcome might possibly be related to etiology, but symptoms of ataxia and opsoclonus were not improved by removal of a neuroblastoma.